Using first-principles calculations and molecular dynamics simulations,
we theoretically explored the potential applications of hexagonal boron
nitride (h-BN) for H-2/CH4 separation. The h-BN with appropriate pores
possesses excellent H-2/CH4 selectivity (>10(5) at room temperature).
Furthermore, the adsorption energies (0.1 eV more or less) of both H-2
and CH4 on the designed monolayer membranes are sufficiently low to
prevent the blocking of the nanopores in a realistic separating process.
Particularly, we demonstrate a highly promising membrane (h-BN with a
triangular pore and a N9H9 rim) with a calculated diffusion barrier of
0.01 eV for H-2 diffusion, and the simulated flux of H-2 across the
single layer is as large as 4.0 x 10(7) GPU at 300 K. Additionally, the
estimated permeability of H-2 significantly exceeds the industrially
accepted standard for gas separation over a broad temperature range.
Therefore, our results suggest that porous boron nitride nanosheets will
be applicable as new membranes for gas separation.